docs: def getSampleFrequency(self,chn):
          """
          Returns the samplefrequency of signal edfsignal.
  
          Parameters
          ----------
          chn : int
              channel number
  
          Examples
          --------
          >>> import pyedflib
          >>> f = pyedflib.data.test_generator()
          >>> f.getSampleFrequency(0)==200.0
          True
          >>> f._close()
          >>> del f
  
          """
          if 0 <= chn < self.signals_in_file:
              return round(self.samplefrequency(chn))
          else:
              return 0